The optical transmission of information through high pressure mediums has increased greatly. Undersea instrumentation and submersibles have more optical information transfer capabilities, partially due to the proven advantages of transmitting by light through fiber optics. The fiber optics, in addition to their well known data transmission capabilities, have certain advantages which make them attractive for penetrating a high pressure hull. One advantage is that their small size reduces the problems normally associated with pressure hull penetrations otherwise made by bulky metal conductors.
One design which recognizes the advantages of employing an optical penetrator is disclosed by John T. Redfern in his U.S. Pat. No. 3,825,320 entitled High-Pressure Optical Bulkhead Penetrator. A cylindrical or tapered plug of glass or cylindrical or tapered bundle of fiber optics is bonded within an accommodatingly shaped bore in a bushing. However, because O-rings and resin adhesives were included and the location of the plugs and bundles within the bores were not precisely made, it might be difficult to reliably fabricate a hermetical seal along the penetration. Experiences have demonstrated that adhesive boundaries may not be hermetic when quality assurances of a uniform bonding are not guaranteed. Most epoxies and polymers permit the passage of vapor over a period of time under the extreme pressure differentials encountered in deep ocean applications. In some penetrators, creep of the adhesive due to nonuniformity may create leaks. In addition, the smallness of the dimension of the ferrules inserted into the Redfern penetrator may affect alignment of the fibers and compromise the data transfer capability of the penetrator.
The Fiber Optic Connector Assembly of Michael A. Dassele et al., disclosed in U.S. Pat. No. 4,222,629 provides a hermetically sealed coupler. However, glass frit bonding fuses the whole arrangement together so that failure of anything from the fiber to the electrooptic conversion element requires that the whole assembly be discarded. If a different electrooptic function is desired, the whole unit must be replaced.
Thus, there is a continuing need in the state-of-the-art for a method of fabricating a penetrator capable of optically transmitting information through a high pressure differential wall that assures reliable long-term operation.